The Simpsons has been stale for over a decade. How it survives is a mystery to me. It long ago became everything it once made fun of.
The Cleveland Show is unwatchable.
South Park remains brilliant, but for whatever reason I don't watch it as much. Might just be a timing thing. But I'd say pound for pound Family Guy is probably funnier. Plus Family Guy makes a lot of New England references and in-jokes. One of the funniest ones was when Peter did the "Spirit of Massachusetts" commercial, parodying a famously awful ad campaign that ran for several years on local TV.